1. Field of the Invention
The present invention pertains to patient interfaces for delivering a flow of breathing gas to a patient and, more particular, to an improved sizing gauge that facilitates selection of a patient interface that is sized appropriately for the patient.
2. Description of the Related Art
There are numerous situations where it is necessary or desirable to deliver a flow of breathing gas non-invasively to the airway of a patient, i.e., without intubating the patient or surgically inserting a tracheal tube in their esophagus. For example, it is known to ventilate a patient using a technique known as non-invasive ventilation. It is also known to deliver continuous positive airway pressure (CPAP) or variable airway pressure, which varies with the patient's respiratory cycle, to treat a medical disorder, such as sleep apnea syndrome, in particular, obstructive sleep apnea (OSA), or congestive heart failure.
Non-invasive ventilation and pressure support therapies involve the placement of a respiratory patient interface device including a patient interface that is typically secured on the face of a patient by a headgear assembly. The patient interface may be, without limitation, a nasal mask that covers the patient's nose, a nasal cushion having nasal prongs that are received within the patient's nares, a nasal/oral mask that covers the nose and mouth, or full face mask that covers the patient's face. It is known to maintain such devices on the face of a wearer by a headgear having one or more straps adapted to fit over/around the patient's head. Because such respiratory patient interface devices are typically worn for an extended period of time, it is important for the headgear to maintain the patient interface in a desired position while doing so in a manner that is comfortable to the patient.
While many mask apparatuses have been generally been effective for their intended purposes, they have not been without limitation. For instance, nasal masks, nasal/oral masks, full face masks, and other types of patient interfaces typically are manufactured in a limited number of sizes and shapes that are intended to fit nearly all patients. However, due to the great variability in the facial geometry of the various patients who need a patient interface, difficulty has been encountered in selecting the patient interface that is sized most appropriately for any given patient.